Example for Configuring Multi-hop BFD

This section provides an example for configuring multi-hop BFD to rapidly monitor a multi-hop link on a network.

Networking Requirements

BFD sessions can be established to rapidly monitor multi-hop links. As shown in Figure 1, BFD in asynchronous mode is configured to monitor the multi-hop link between Device A and Device C.

Figure 1 Multi-hop BFD

Interfaces 1 through 2 in this example are GE 0/1/0, GE 0/1/8, respectively.

Precautions

BFD sessions must be established on both ends.

Configuration Roadmap

The configuration roadmap is as follows:

Configure a BFD session on Device A to monitor the multi-hop link from Device A to Device C.
Configure a BFD session on Device C to monitor the multi-hop link from Device C to Device A.

Data Preparation

To complete the configuration, you need the following data:

Peer IP address monitored by BFD
Names of the BFD sessions for detecting the multi-hop link
Local and remote discriminators of BFD sessions

Procedure

Configure Device A, Device B, and Device C to be routable.

# Assign an IP address to the interface on Device A.

<HUAWEI> system-view
[~HUAWEI] sysname DeviceA
[*HUAWEI] commit
[~DeviceA] interface GigabitEthernet 0/1/0
[~DeviceA-GigabitEthernet0/1/0] undo shutdown
[*DeviceA-GigabitEthernet0/1/0] ip address 10.1.1.1 24
[*DeviceA-GigabitEthernet0/1/0] commit
[~DeviceA-GigabitEthernet0/1/0] quit

# Assign IP addresses to the interfaces on Device B.

<HUAWEI> system-view
[~HUAWEI] sysname DeviceB
[*HUAWEI] commit
[~DeviceB] interface GigabitEthernet 0/1/0
[~DeviceB-GigabitEthernet0/1/0] undo shutdown
[*DeviceB-GigabitEthernet0/1/0] ip address 10.1.1.2 24
[*DeviceB-GigabitEthernet0/1/0] commit
[~DeviceB-GigabitEthernet0/1/0] quit
[~DeviceB] interface GigabitEthernet 0/1/8
[~DeviceB-GigabitEthernet0/1/8] undo shutdown
[*DeviceB-GigabitEthernet0/1/8] ip address 10.2.1.1 24
[*DeviceB-GigabitEthernet0/1/8] commit
[~DeviceB-GigabitEthernet0/1/8] quit

# Assign an IP address to the interface on Device C.

<HUAWEI> system-view
[~HUAWEI] sysname DeviceC
[*HUAWEI] commit
[~DeviceC] interface GigabitEthernet 0/1/0
[~DeviceC-GigabitEthernet0/1/0] undo shutdown
[*DeviceC-GigabitEthernet0/1/0] ip address 10.2.1.2 24
[*DeviceC-GigabitEthernet0/1/0] commit
[~DeviceC-GigabitEthernet0/1/0] quit

# Configure static routes.

[~DeviceA] ip route-static 10.2.1.0 255.255.255.0 10.1.1.2
[*DeviceA] commit
[~DeviceC] ip route-static 10.1.1.0 255.255.255.0 10.2.1.1 
[*DeviceC] commit

Configure BFD to monitor the multi-hop link between Device A and Device C.

# Enable BFD on Device A and establish a BFD session to monitor the link from Device A to Device C. You do not need to bind the BFD session to an interface.

[~DeviceA] bfd
[*DeviceA-bfd] quit
[*DeviceA] bfd atoc bind peer-ip 10.2.1.2
[*DeviceA-bfd-session-atoc] discriminator local 10
[*DeviceA-bfd-session-atoc] discriminator remote 20
[*DeviceA-bfd-session-atoc] commit
[~DeviceA-bfd-session-atoc] quit

# Enable BFD on Device C and establish a BFD session to monitor the link from Device C to Device A. You do not need to bind the BFD session to an interface.

[~DeviceC] bfd
[*DeviceC-bfd] quit
[*DeviceC] bfd ctoa bind peer-ip 10.1.1.1
[*DeviceC-bfd-session-ctoa] discriminator local 20
[*DeviceC-bfd-session-ctoa] discriminator remote 10
[*DeviceC-bfd-session-ctoa] commit
[~DeviceC-bfd-session-ctoa] quit

Verify the configuration.

After completing the configurations, run the display bfd session all verbose command on Device A and Device C. The command output shows that a multi-hop BFD session has been established and its status is Up.

The following example uses the command output on Device A.

[~DeviceA] display bfd session all verbose
(w): State in WTR 
(*): State is invalid
------------------------------------------------------------------------------
  (Multi Hop)  State : Up                       Name : atoc
------------------------------------------------------------------------------
  Local Discriminator    : 10             Remote Discriminator    : 20
  Session Detect Mode    : Asynchronous Mode Without Echo Function
  BFD Bind Type          : Peer Ip Address
  Bind Session Type      : Static
  Bind Peer IP Address   : 10.2.1.2
  Bind Interface         : -   
  FSM Board Id           : 1                TOS-EXP                : 7
  Min Tx Interval (ms)   : 10               Min Rx Interval (ms)   : 10
  Actual Tx Interval (ms): 10               Actual Rx Interval (ms): 10
  Local Detect Multi     : 3                Detect Interval (ms)   : 30
  Echo Passive           : Disable          Acl Number             : -
  Destination Port       : 4784             TTL                    : 254  
  Proc Interface Status  : Disable          Process PST            : Disable
  WTR Interval (ms)      : 0                Config PST             : Disable
  Active Multi           : 3
  Last Local Diagnostic  : No Diagnostic
  Bind Application       : No Application Bind
  Session TX TmrID       : 2584985432       Session Detect TmrID   : -
  Session Init TmrID     : -                Session WTR TmrID      : -
  Session Echo Tx TmrID  : -
  Session Description    : -
------------------------------------------------------------------------------
       Total UP/DOWN Session Number : 1/0

# Run the shutdown command on GE 0/1/0 of Device A to simulate a link fault.

[~DeviceA] interface GigabitEthernet 0/1/0
[~DeviceA-GigabitEthernet0/1/0] shutdown
[*DeviceA-GigabitEthernet0/1/0] commit
[~DeviceA-GigabitEthernet0/1/0] quit

Run the display bfd session all verbose command on Router A. The command output shows that the status of the BFD session is Down.

The following example uses the command output on Device A.

[~DeviceA] display bfd session all verbose
(w): State in WTR 
(*): State is invalid
------------------------------------------------------------------------------
  (Multi Hop)  State : Down                       Name : atoc
------------------------------------------------------------------------------
  Local Discriminator    : 10             Remote Discriminator    : 20
  Session Detect Mode    : Asynchronous Mode Without Echo Function
  BFD Bind Type          : Peer Ip Address
  Bind Session Type      : Static
  Bind Peer IP Address   : 10.2.1.2
  Bind Interface         : -   
  FSM Board Id           : 1                TOS-EXP                : 7
  Min Tx Interval (ms)   : 10               Min Rx Interval (ms)   : 10
  Actual Tx Interval (ms): 10               Actual Rx Interval (ms): 10
  Local Detect Multi     : 3                Detect Interval (ms)   : 30
  Echo Passive           : Disable          Acl Number             : -
  Destination Port       : 4784             TTL                    : 254  
  Proc Interface Status  : Disable          Process PST            : Disable
  WTR Interval (ms)      : 0                Config PST             : Disable
  Active Multi           : 3
  Last Local Diagnostic  : No Diagnostic
  Bind Application       : No Application Bind
  Session TX TmrID       : 2584985432       Session Detect TmrID   : -
  Session Init TmrID     : -                Session WTR TmrID      : -
  Session Echo Tx TmrID  : -
  Session Description    : -
------------------------------------------------------------------------------
       Total UP/DOWN Session Number : 0/1

Configuration Files

Device A configuration file

#
 sysname DeviceA
#
 bfd
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.1.1.1 255.255.255.0
#
ip route-static 10.2.1.0 255.255.255.0 10.1.1.2
#
bfd atoc bind peer-ip 10.2.1.2
 discriminator local 10
 discriminator remote 20
return

Device B configuration file

#
 sysname DeviceB
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.1.1.2 255.255.255.0
#
interface GigabitEthernet0/1/8
 undo shutdown
 ip address 10.2.1.1 255.255.255.0
return

Device C configuration file

#
 sysname DeviceC
#
 bfd
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.2.1.2 255.255.255.0
#
ip route-static 10.1.1.0 255.255.255.0 10.2.1.1
#
bfd ctoa bind peer-ip 10.1.1.1
 discriminator local 20
 discriminator remote 10
return